The present invention generally relates to a system for transferring a liquid anesthetic agent from an anesthetic bottle to an anesthetic vaporizer. More specifically, the present invention relates to an anesthetic vaporizer filling system that includes a unique valve arrangement and keyed engagement system that prevents the anesthetic agent from being released to atmosphere during filling and insures that only the desired type of anesthetic agent can be discharged into the anesthetic vaporizer.
Anesthetic agents are typically volatile substances with relatively low boiling points and high vapor pressures. Anesthetic agents can be flammable and explosive in both their liquid and vapor states. Further, inhalation of vapor by healthcare personnel in the area near where the anesthetic agent is being used can cause drowsiness. An anesthetic agent is administered to a patient during anesthesia by means of an anesthetic vaporizer. The agent is supplied to the patient from an internal sump within the vaporizer as a vapor, while the agent is stored within the sump as a liquid. The anesthetic agent is typically mixed with oxygen and nitrous oxide prior to its delivery to the patient for inhalation.
Devices and filling systems have been designed for the transfer of the anesthetic agent from a supply container, such as an anesthetic bottle, to the vaporizer sump through a closed system that minimizes the escape of anesthetic gas to the atmosphere. These devices are designed so that during set-up and disassembly procedures, the anesthetic bottle is not open and exposed to atmosphere.
One example of such a system is shown in the Grabenkort U.S. Pat. No. 5,505,236. In this patent, the filling system lacks implementation of a filler probe seal, which in turn forces the implementation of a fill vent. The fill vent is required to prevent increased vapor pressure within the sump and filling system from causing egress of anesthetic agent between the filler probe (bottle) and filler receiver (vaporizer). As a result, the fill vent allows release of anesthetic vapor to atmosphere during the filling process (most notably when filling a vaporizer with dry sump and wick). Further, the anesthetic bottle includes a plunger that is biased by a first spring. When the anesthetic bottle is pressed into the filler of the anesthetic vaporizer, the plunger contacts the outer surface of an inlet valve member that in turn is biased to a closed position by a second spring. The first and second springs are configured such that the second spring holding the inlet valve member is weaker than the first spring biasing the plunger in the anesthetic bottle. This configuration of springs insures that the inlet valve member opens prior to anesthetic agent leaving the anesthetic bottle. Therefore, the relative spring strengths of the pair of springs in the Grabenkort reference are critical to insure that the anesthetic agent is not released to atmosphere. If the strength of either spring changes after repeated use, or if one of the springs is not properly calibrated, anesthetic vapor could be released to atmosphere. This system, therefore, has several drawbacks that need to be addressed.
Presently, many types of anesthetic agents are available for use during anesthesia. These anesthetic agents include, but are not limited, to: Enflurane, Halothane, Isoflurane and Sevoflurane. Each of these anesthetic agents has different properties and vaporizers are typically designed to deliver the anesthetic agents differently depending upon the properties of the anesthetic agent. Therefore, it is important that only the correct type of anesthetic agent is delivered to the vaporizer.
Currently, the International Standardization Organization (ISO) has developed standard 5360:1993 that mandates the inclusion of a pair of protrusions on an anesthetic agent bottle. The standard calls for a specific angle between the protrusions around the bottle that is based upon the type of anesthetic agent contained within the anesthetic bottle. Because the anesthetic container for each type of anesthetic agent has its own set of protrusions and color, and because a corresponding connector device for the anesthetic bottle fits only the type of vaporizer designed for that type of anesthetic, the probability of inadvertently using the wrong type of anesthetic in a vaporizer has been greatly reduced.
Although the anesthetic bottle may include protrusions specifically positioned based on the type of anesthetic contained within the bottle and can be emptied by keyed connector tubes, typical anesthetic bottles do not include a valve arrangement that can be used to prevent loss of the anesthetic agent to atmosphere during filling. Further, the keyed connector tubes are of a small size which reduce the rate of filling the vaporizer, and require manual operation of mechanisms to retain the keyed tubes in the vaporizer while filling, and to operate valving in the vaporizer to receive the anesthetic from the keyed connector tubes. Further, the keyed connector tubes themselves contain no valving to prevent loss of anesthetic vapor from the bottle when the bottle is not connected to the vaporizer, or the loss of liquid from the bottle if the bottle is inverted while not connected to the vaporizer. Further, due to the horizontal nature of the receiving ports in vaporizers for such keyed connector tubes, small amounts of liquid anesthetic persist in the tubing when the keyed connector tubes are disconnected from the vaporizer. This liquid anesthetic is then lost, since it is not retained either in the vaporizer or the keyed connector tubes.
Therefore, a need exists for an anesthetic vaporizer filling system that allows a bottle adapter having a unique valve assembly to be attached to the anesthetic bottle. Further, a need exists for a system having a specifically configured filling station that interacts with the bottle adapter to insure that the anesthetic agent is not released to atmosphere during the filling procedure. Further, a need exists for the filling station of the anesthetic vaporizer to have a unique configuration that receives only a specified type of anesthetic agent.